Contrast Features in Ophthalmology

• In Non-ischaemic CRVO, RAPD is absent or mild in contrast to ischaemic CRVO.

• In contrast to BCC and SCC, SGC occurs more commonly on the upper eyelid where meibomian glands are more numerous.

• In Simple congenital ptosis, In downgaze the ptotic lid is higher than the normal because of poor relaxation of the levator muscle. This is in contrast to acquired ptosis in which the affected lid is either level with or lower than the normal lid on downgaze.

• In contrast to dacryocystitis, there is no nasolacrimal duct obstruction, or lacrimal sac distension or inflammation in Chronic canaliculitis.

• In contrast to orbital cellulitis proptosis and chemosis are absent; visual acuity, pupillary reactions and ocular motility are unimpaired in Preseptal cellulitis.

• In contrast to follicles, a vascular core is present in Papillae.

• In VKC, Eyelid disease is usually mild, in contrast to AKC.

• In contrast to acne vulgaris comedones (blackheads or whiteheads) are absent in Rosacea.

• In contrast to Mooren ulcer the process may also extend into the sclera in PUK.

• Wegener granulomatosis is the second most common systemic association of PUK. In contrast with rheumatoid arthritis ocular complications are the initial presentation in 50% of cases

• In contrast to keratoconus, Fleischer rings and Vogt striae do not occur and acute hydrops is rare in PMD.

• In Tyrosinaemia type 2 (Richner–Hanhart syndrome), In contrast to true herpetic ulcers the lesions are usually bilateral and inferotemporal, corneal sensation is normal, there is lack of response to antiviral therapy, typical terminal bulbs are absent and staining with fluorescein is limited.

• The pigment tends to be concentrated in the inferior sector of the angle in POAG, in contrast to the homogeneous distribution in PDS.

• sarcoid vasculitis involves only veins in a segmental manner and is rarely occlusive. In contrast, BS usually affects both arteries and veins, is diffuse, frequently occlusive and is associated with vitritis, which is uncommon in sarcoid-related vasculitis.

• Posterior scleritis, which can present with a large elevated lesion, but in contrast to melanoma pain is a common feature.

• Melanocytoma (magnocellular naevus) is a rare, distinctive, unilateral, heavily pigmented congenital hamartoma which is seen most frequently in the optic nerve head but which can rarely arise anywhere in the uvea. In contrast to choroidal melanoma, melanocytomas are relatively more common in dark-skinned individuals and have a female predominance. In most cases the tumour is stationary with little tendency to change.

• In macular disease, there is positive scotoma, in which patients complain of something obstructing their central vision, is a symptom of more severe disease. This is in contrast to optic neuropathy which typically causes a missing area in the visual field (a negative scotoma).

• In Choroideremia, In contrast to primary retinal dystrophies, the fovea is spared until late.

• Neurological anomalies are frequently present in Constant (early-onset) exotropia, in contrast with infantile esotropia.

• In NAION, Dyschromatopsia is usually proportional to the level of visual impairment, in contrast with optic neuritis in which colour vision may be severely impaired when visual acuity is reasonably good.

- compiled & published by Dr Dhaval Patel MD AIIMS